goitre vs goiter

goitre and goiter both are nouns.

Word	Noun	Adjective	Verb	Adverb
goitre	Yes	No	No	No
goiter	Yes	No	No	No

As nouns, goitre and goiter are synonyms defined as:

goitre and goiter: abnormally enlarged thyroid gland; can result from underproduction or overproduction of hormone or from a deficiency of iodine in the diet

Other synonyms of goitre include struma, thyromegaly.

goitre (noun)	goiter (noun)
abnormally enlarged thyroid gland; can result from underproduction or overproduction of hormone or from a deficiency of iodine in the diet	abnormally enlarged thyroid gland; can result from underproduction or overproduction of hormone or from a deficiency of iodine in the diet